Broach assembly



Feb. 24, 1953 5, KOPEc 2,629,294

BROACH ASSEMBLY Filed Nov. 5, 1951 14 3a 7 a [7 a 8 34 5 /2 H I [NW/V7 UR STANLEY J- ATTUPNEX Patented Feb. 24, 1953 UNITED STATES PATENT OFFICE BROACH ASSEMBLY Stanley J. Kopec, Northville, Mich. Application November 5, 1951, Serial No. 254,897

9 Claims. 1

This invention relates generally to breaches and more particularly to broaches for cutting helical teeth on the bands surrounding a projectile.

In utilizing broaches to cut helical teeth, it has heretofore required a ten or more section broach to cut the helical teeth. It has also been necessary to use a helixing driver and clamping means for holding the projectile while it passes through the broach rings. This clamping means is necessary to prevent the projectile from wandering from a true helical path. These prior breaches have had the same tooth form on each broach ring, each successive ring having a slightly smaller minor diameter. Only a small out can be taken by each broach with these prior broaches from either the root or sides of a tooth in that there is no place for the chips to go. They are usually arranged so that one broach ring cuts the sides of a tooth and the next broach ring the roots so that the chips will not interfere. They generate considerable heat and they are difiicult to lubricate at the cutting points of the teeth.

It is, accordingly, an object of my invention to provide a novel broach for cutting helical teeth which is simple in construction, economical in cost, economical in manufacture, and eificient in operation.

Another object of my invention is to provide a a novel broach for cutting helical teeth whereby one section thereof rough cuts the teeth and the last section finishes the teeth.

Another object of my invention is to provide novel means for cooling a broach so that high production may be obtained.

Another object of my invention is to provide novel means for lubricating broach teeth.

Another object of my invention is to provide a novel machine utilizing a two section broach for cutting helical teeth, particularly on the bands surrounding a projectile.

Another object of my invention is to provide a depository for the chips in a broach assembly.

Other objects of my invention will become evident from the following detailed description, taken in conjunction with the accompanying drawings, in which Fig. l is a plan view of my novel broach assemly;

Fig. 2 is a view taken on the line 2--2 of Fig. 1;

Fig. 3 is a side elevational fragmentary view of a guide member disposed in alignment with the broach for guiding a projectile through the broach; and

Fig. 4 is a fragmentary view showing a member for pushing a projectile through my novel broach assembly.

Referring now to the drawings, I show in Figs. 1 and 2 a cupshaped supporting member I having an axially extending aperture 2 tapered at 3 and counterbored at t. Annular broach rings 5 and 6 are disposed in the counterbore 4 in axial alignment, the rings 5 and 5 having longitudinally extending grooves I and 8 for engaging keys 9 in the counterbore 4. The broach ring 5 has helical shaped cutting teeth H for cutting the major portion of the sides and roots of teeth of a band on a projectile passing through the broach and the teeth i2 on the broach ring 6 are of a predetermined size and diameter to cut the finished tooth profile required on the band of the projectile. Each ring 5 and B has annular, semi-circular shaped, intermediate grooves l4 and I5 in the top side thereof and each ring 5 and B has an inner marginal groove I6 and I1. The groove it on the broach ring 5 merges with a marginal groove l8 on the under side of a pilot ring 23 to form an annular, open, downwardly inclined groove and the groove I! on the broach ring 5 merges with a marginal groove 22 on the under side of the broach ring 5 to form an open, downwardly inclined, annular groove. The pilot ring 23 is disposed in the counterbore l of the support member I in axial alignment with the broach rings 5 and 6. The pilot ring 23 is connected to the broach ring 5 by screw bolts 24, the heads 25 of which nest in counterbores 26 and the threaded ends 21 of which engage threaded apertures 28 in the upper side of the broach ring 5. The broach rings 5 and 6 are connected together and to the support member I by axially extending screw bolts 30 having heads 3! nested in counterbores 32 in the lower side of the support member i, the threaded ends 33 of the screw bolts 32 threadably engaging threaded apertures 34 and 35 in the broach rings 5 and 6, respectively. The annular grooves l4 and I5 are connected with the open, inner annular grooves by passages 36 and 31 which are tangent to the outer diameter of the open grooves so that air passing from the grooves 14 and I5 to the open inner grooves will move circularly therearound to cool the teeth of the broach rings and to cool the chips therein and move them in a. circular path. The inner open grooves provide a depository for chips cut from the bands of the projectiles. Air is passed to the grooves I4 and i5 through passageways 38 connected to a suitable source of air. Lubricant likewise may be passed into the circular 2 grooves l4 and I5 through passageways 39 whereby it passes to the cutting teeth of the broach rings 5 and G to provide adequate lubrication.

The axially extending width of the inner open grooves is preferably less than the width of the teeth to be formed on the workpiece in order that the workpiece will move in a true helical path without any tendency to misalignment. The internal diameter of the pilot ring 23 is approximately the size of the diameter of the projectile so as to guide the projectile in a straight line through the broach assembly. The pushing member shown in Fig. 4 is merely conventional and comprises a conventional rotatable shaft 40 which engages the end of the projectile to push it through the broach assembly. After the projectile passes through the broach assembly, the nose 42 thereof nests in the conical shaped recess 43 in the guide member M which is retractible when the shaft 49 pushes the projectile through the breach assembly to guide the projectile in a straight path through its passage in the broach ring assembly.

It will be evident from the foregoing description that I have provided a novel broach ring assembly which permits the completion of a breaching operation in a matter of seconds. which increases production of present broach rings several times, which only needs two broach rings in the assembly, which is well lubricated, which keeps cool, and which provides for the chips resulting from the cutting operation.

Various changes may be made in the specific embodiment of my invention without departing from the spirit thereof or from the scope of the appended claims.

What I claim is:

1. In a broach assembly, in combination, a holder. annular broach rings disposed in said holder, each of said broach rings having an annular intermediate groove on the upper side thereof and an annular marginal groove on the inner edge thereof, and a pilot ring disposed in axial alignment with said broach rings for axially piloting a cylindrical workpiece through said broach rings, said broach rings having passages connecting said intermediate annular grooves and said marginal grooves.

2. In a broach assembly as set forth in claim 1 wherein the under sides of said pilot ring and said broach ring adjacent thereto are margin-ally grooved to define an annular open groove.

3. In a broach assembly as set forth in claim 1 wherein the minor internal diameters of said broach rings progressively decrease.

4. In a broach assembly as set forth in claim 1 wherein the teeth of said broach rings are designed to out both the roots and the sides of teeth on a cylindrical workpiece.

5. In a breach assembly as set forth in claim 1 wherein both of the inner marginal edges of said broach rings are grooved whereby grooves on adjacent broach rings merge to define an open annular groove.

6. In a broach assembly as set forth in claim 1 .4 wherein said passages are tangent to the periphery oi the groove on the inner edges of said broach rings.

'7. A broach assembly comprising a cup-shaped member having a bore with a tapered end and a counterbore, annular broach rings axially aligned in said counterbore with internal cutting teeth of difierent minor diameters, said broach rings having annular grooves in the upper side thereof, marginal grooves on the inner margins thereof, and tangentially extending passages between said annular grooves and said inner marginal grooves, a pilot ring disposed in said counterbore in axial alignment with said broach rings, means for securing said broach rings and said pilot ring in said counterbore, and means for securing a source of fluid to said grooves.

8. A machine for cutting helical teeth on the bands of a projectile comprising a cup-shaped holding member having an axial bore with a counterbore, annular broach rings having cutting teeth with progressively smaller internal minor diameters disposed in the counterbore of said holding member, a pilot ring disposed in the counterbore of said holding member in axial alignment with said broach rings, said broach rings having intermediate circular grooves in the upper side thereof, marginal grooves on the inner marginal edges thereof, and passages between said intermediate grooves and said marginal grooves tangential to said marginal grooves, means for securing said broach rings in said holding member, a rotatable pusher for pushing a projectile through said broach rings, and a retractible guiding member with a conical shaped recess for engaging the nose of a projectile when it passes through said broach rings to direct it in a straight path.

9. A breaching machine for cutting helical teeth on bands of a projectile comprising a broach assembly having axially aligned, annular broach rings having internal helical cutting teeth with progressively decreasing minor internal diameters, said broach rings having annular grooves intermediate thereof, marginal grooves on the inner edges thereof, and passages tangential to said marginal grooves connecting said intermediate grooves and said marginal grooves, a source of air for passage to said annular grooves, means for pushing a projectile through said broach rings, and retrac'tible means for guiding the nose of a projectile in an axial path after it passes through said broach rings.

STANLEY J. KOPEC.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,511,298 Schinnerer June 13, 1950 FOREIGN PATENTS Number Country Date 9,438 Great Britain Dec. 31, 1919 866,793 France June 9, 1941 

